Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common human genetic polymorphism. A clinically significant variant is the type A deficiency present in 10-12% of African Americans. G6PD is a major supporter of cellular redox status. Our clinical investigations on young African American trauma patients revealed that after severe trauma, the type A- G6PD deficiency predisposes to the development of bacteremic sepsis, an augmented inflammatory response and worsens anemia. The defect also alters the trauma-induced monocyte responses. We will investigate the impact of the defect on the sepsis-associated multiple organ dysfunction/failure and mortality after major trauma. We will test if a compromised RBC function and an altered activation status of the reticolo-endothelial/monoculear phagocyte system contribute to the adverse clinical effects of the deficiency. The study use G6PD deficient and nondeficient human endothelial cells (HUVEC), monocytes and neutrophils and an animal model. Hypotheses: 1: After severe trauma, the sepsis-associated mortality is greater in G6PD deficient patients than non-deficient patients. The adverse clinical course of G6PD deficient patients is associated with a diminished production of anti- inflammatory cytokines by monocytes, increased hemolysis, and decreased RBC deformability. The prospective cohort study will compare the clinical parameters in G6PD deficient and nondeficient patients after major trauma (ISS>13) and the time dependent changes in cytokine patterns representative of the proinflammatory/anti-inflammatory balance in leukocytes. Alterations in RBC deformability, lipid peroxidation, nitrosylated protein, nitroso-thiol and glutathione content will also be followed. 2: After oxidative stress, G6PD deficient endothelial cells and monocytes display an augmented pro-inflammatory response compared to non-deficient cells. Activation of redox-dependent transcription factors ( NFkB,AP1,SP1) and redox status (GSH/GSSG) and the accompanying changes in cytokine production will be determined after ischemia- reoxygenation or chemically-induced oxidative stress in deficient and non-deficient HUVEC and monocytes. 3. G6PD deficiency diminishes the antioxidant capacity of endothelial cells more severely than the antioxidant capacity of phagocytes which results in an enhanced phagocyte-mediated endothelial dysfunction. Phagocyte-mediated endothelial cell apoptosis/injury will be measured in co-cultures using deficient or non-deficient cells. Using specific inhibitors of G6PD in an animal model will test endothelial cell dysfunction. The studies will elucidate if the adverse clinical effects of G6PD deficiency are manifested in elevated mortality and worsening organ dysfunction after injuries. The study will reveal important and novel information on the potential mechanisms, including RBC dysfunction, monocyte activation, and the role of redox regulated gene expression that is responsible for the adverse clinical effects of G6PD deficiency in trauma patients.